Journal of Microbiology

Jin Park

1 Article

Gly184 of the Escherichia coli cAMP receptor protein provides optimal context for both DNA binding and RNA polymerase interaction: Matt N. Hicks , Sanjiva Gunasekara , Jose Serate , Jin Park , Pegah Mosharaf , Yue Zhou , Jin-Won Lee , Hwan Youn; J. Microbiol. 2017;55(10):816-822. Published online September 28, 2017; DOI: https://doi.org/10.1007/s12275-017-7266-x

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The Escherichia coli cAMP receptor protein (CRP) utilizes the helix-turn-helix motif for DNA binding. The CRP’s recognition helix, termed F-helix, includes a stretch of six amino acids (Arg180, Glu181, Thr182, Val183, Gly184, and Arg185) for direct DNA contacts. Arg180, Glu181 and Arg185 are known as important residues for DNA binding and specificity, but little has been studied for the other residues. Here we show that Gly184 is another F-helix residue critical for the transcriptional activation function of CRP. First, glycine was repeatedly selected at CRP position 184 for its unique ability to provide wild type-level transcriptional activation activity. To dissect the glycine requirement, wild type CRP and mutants G184A, G184F, G184S, and G184Y were purified and their in vitro DNA-binding activity was measured. G184A and G184F displayed reduced DNA binding, which may explain their low transcriptional activation activity. However, G184S and G184Y displayed apparently normal DNA affinity. Therefore, an additional factor is needed to account for the diminished transcriptional activation function in G184S and G184Y, and the best explanation is perturbations in their interaction with RNA polymerase. The fact that glycine is the smallest amino acid could not fully warrant its suitability, as shown in this study. We hypothesize that Gly184 fulfills the dual functions of DNA binding and RNA polymerase interaction by conferring conformational flexibility to the F-helix.

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cAMP-independent DNA binding of the CRP family protein DdrI from Deinococcus radiodurans
Yudong Wang, Jing Hu, Xufan Gao, Yuchen Cao, Shumai Ye, Cheng Chen, Liangyan Wang, Hong Xu, Miao Guo, Dong Zhang, Ruhong Zhou, Yuejin Hua, Ye Zhao, Paul Babitzke
mBio.2024;[Epub] CrossRef
Unexpected Requirement of Small Amino Acids at Position 183 for DNA Binding in the Escherichia coli cAMP Receptor Protein
Marcus Carranza, Amanda Rea, Daisy Pacheco, Christian Montiel, Jin Park, Hwan Youn
Journal of Microbiology.2024; 62(10): 871. CrossRef
cAMP Activation of the cAMP Receptor Protein, a Model Bacterial Transcription Factor
Hwan Youn, Marcus Carranza
Journal of Microbiology.2023; 61(3): 277. CrossRef

Jin Park

2 Articles

Erratum: Unexpected Requirement of Small Amino Acids at Position 183 for DNA Binding in the Escherichia coli cAMP Receptor Protein: Marcus Carranza, Amanda Rea, Daisy Pacheco, Christian Montiel, Jin Park, Hwan Youn; J. Microbiol. 2024;62(12):1177-1177. Published online November 6, 2024; DOI: https://doi.org/10.1007/s12275-024-00189-y

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Unexpected Requirement of Small Amino Acids at Position 183 for DNA Binding in the Escherichia coli cAMP Receptor Protein: Marcus Carranza, Amanda Rea, Daisy Pacheco, Christian Montiel, Jin Park, Hwan Youn; J. Microbiol. 2024;62(10):871-882. Published online September 6, 2024; DOI: https://doi.org/10.1007/s12275-024-00169-2

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Abstract

The Escherichia coli cAMP receptor protein (CRP) relies on the F-helix, the recognition helix of the helix-turn-helix motif, for DNA binding. The importance of the CRP F-helix in DNA binding is well-established, yet there is little information on the roles of its non-base-contacting residues. Here, we show that a CRP F-helix position occupied by a non-base-contacting residue Val183 bears an unexpected importance in DNA binding. Codon randomization and successive in vivo screening selected six amino acids (alanine, cysteine, glycine, serine, threonine, and valine) at CRP position 183 to be compatible with DNA binding. These amino acids are quite different in their amino acid properties (polar, non-polar, hydrophobicity), but one commonality is that they are all relatively small. Larger amino acid substitutions such as histidine, methionine, and tyrosine were made site-directedly and showed to have no detectable DNA binding, further supporting the requirement of small amino acids at CRP position 183. Bioinformatics analysis revealed that small amino acids (92.15% valine and 7.75% alanine) exclusively occupy the position analogous to CRP Val183 in 1,007 core CRP homologs, consistent with our mutant data. However, in extended CRP homologs comprising 3700 proteins, larger amino acids could also occupy the position analogous to CRP Val183 albeit with low occurrence. Another bioinformatics analysis suggested that large amino acids could be tolerated by compensatory small-sized amino acids at their neighboring positions. A full understanding of the unexpected requirement of small amino acids at CRP position 183 for DNA binding entails the verification of the hypothesized compensatory change(s) in CRP.

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SPD_0410 negatively regulates capsule polysaccharide synthesis and virulence in Streptococcus pneumoniae D39
Ye Tao, Li Lei, Shuhui Wang, Xuemei Zhang, Yibing Yin, Yuqiang Zheng
Frontiers in Microbiology.2025;[Epub] CrossRef

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